docs: def get_document_list(self):
          """
          Retrieves all documents included in this project.
          """
          try:
              return self.__dict__['document_list']
          except KeyError:
              obj_list = DocumentSet([
                  self._connection.documents.get(i) for i in self.document_ids
              ])
              self.__dict__['document_list'] = obj_list
              return obj_list